- Relocation of underground utilities for Midtown Tunnel Construction
- Horizontal Directional Drilling Design for new 36-in diameter raw water pipeline beneath Elizabeth River
- Abandoned wharf filled with rubble and timber piles within drill path
- Noise mitigation required due to proximity to hospital
Constructed in 1962, the Midtown Tunnel carries US Route 58 beneath the Elizabeth River links Norfolk and Portsmouth, VA. Originally configured to allow both east and westbound traffic, it was subsequently changed to be eastbound only and a new westbound tube was constructed adjacent to the existing eastbound tunnel. As part of the overall project, existing underground utilities had to be relocated and or improved.
Brierley Associates was retained to provide a variety of preliminary HDD engineering and evaluation services to relocate a raw water line and sewer force main that cross beneath the westbound tunnel construction footprint and under the Elizabeth River in Norfolk.
Components of the relocated utilities included 4,470 feet (1,362m) of 36-in (91cm) diameter coated steel raw water supply pipe and 3,610 feet (1,100m) of 42-in (107cm) diameter coated steel sewer force main. Brierley provided these services for each proposed crossing via Horizontal Directional Drilling: preparation of a Feasibility and Preliminary Engineering Reports; pipe material selection; coating and size assessment; recommendations; preliminary trenchless design and, environmental contingency planning. The new 36-in (91cm) diameter raw water pipeline was constructed and placed in service in May 2013. However, the final design and construction of the 42-in (106cm) diameter sewer pipe was not completed as it was discovered that the existing line was actually outside of the new westbound tube footprint.